The present invention is directed to processes for preparing bland oilseed products, and more particularly, to such processes for preparing edible oilseed products utilizing fermentation techniques which impart buttery or dairy-like flavors to the oilseed product. The present invention is also directed to dairy like products such as imitation cream cheese products derived from oilseed components as milk or caseinate replacers.
Substantial technical effort has been directed to the utilization of oilseed products, particularly including soybean products which are perceived as beany, grassy and cereal-like in flavor with a chalky or unpleasant mouth-coating texture. Considerable attention has been directed toward improving the flavor and texture of such oilseed materials by microbial fermentation. In this regard, the production of tempeh, miso and other oriental products has utilized fermentative techniques, principally fermentation with molds. More recently, soy has been fermented with yeast [e.g., U.S. Pat. No. 3,810,997] and with bacteria [e.g., Mital and Steinkraus, J. Food Protection, 42, 895-899 (1979)] in order to improve flavor and texture. Yeast and bacteria have been used to ferment soy flour and soymilk, that is, the less refined soy products. Such microorganisms may metabolize the natural substrates found in these products, such as sugars, lipids or proteins to produce flavors which have been described inter alia as sour, astringent, soapy, bitter or brothy. The major use of bacterial fermentations has been with full-fat soy, particularly including soymilk in efforts to modify both flavor and texture of full-fat soy to convert the soymilk into soy "dairy products" like yogurt and sour cream. The principal flavor component of the fermented soymilk was lactic acid, which arose from the bacterial metabolism of sucrose, raffinose or stachyose, the three principal sugars in soymilk.
There have also been attempts to produce dairy-like flavors more associated with buttermilk and cream cheese from soy products. These flavors result from the bacterial production of two volatile compounds, namely diacetyl and acetylmethylcarbinol (AMC). Production of diacetyl and AMC in soymilk using Streptococcus species known to produce these compounds in cow's milk has been reported in soymilk after extended incubation [e.g., 48 hours, Gehrke, et al., J. Dairy Sci., 31, 213-222 (1948)]. Certain species of Lactobacillus, like L. casei, are known to be capable of diacetyl and AMC production, which has been observed in cow's milk inoculated with L. casei, 40 to 50 hours after inoculation [Bassette, et al., J. Dairy Sci., 50, 167-171 (1957)]. Diacetyl and AMC have been produced from L. casei grown in a broth medium. The addition of the metabolite pyruvate to the growth medium was reported to stimulate the production of flavor volatiles when L. casei was present [Branen, et al., Applied Microbiol., 22, 517-521 (1971); Benito de Cardenas, et al., Milchwissenschaft, 35, 296-300 (1980)].
However, there is a need for improved fermentation processes for manufacturing dairy-like products such as imitation cream cheese of high quality from vegetable oilseed starting materials, and it is an object of the present invention to provide such processes and products.